Refrigerant flow controlling device



April 1951 w. R. WHITNEY 2,548,643

REFRIGERANT FLOW CONTROLLING DEVICE Filed 'Nov. 9, 1946 Inventor: v Willis R. Whitney.

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Z2 23 His Attorn ey Patented Apr. 10, 1951 REFRIGERANT FLOW CONTROLLING DEVICE Willis R. Whitney, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application November 9, 1946, Serial No. 7(l8,9li3 8 Claims. (Cl. 62-427) This invention relates to mechanical refrigerating systems and more particularly to an arrangement for preventing clogging of such systems due to freezing of moisture therein.

Many refrigerating systems use a restricting tube, sometimes referredto as a capillary tube, to maintain the proper pressure difference between the high side and the low side of the system. Moisture is frequently present in the refrigerating system because of incomplete evacuation or drying during manufacture or because of overheating and consequent charring of the motor windings in the hermetically sealed motor compressor units during operation- This moisture will tend to freeze in thecolder parts of the refrigerating system. Difficulty has been experienced in the use of restricting tubes since, because of the small diameter of the passage through such tubes, the freezing of the moisture therein will cause a complete blocking of the passage and hence will render the refrigerating system inoperative. This difficulty is encountered particularly at the outlet, that is,"at the evaporator end, of the restricting. tube, since a lower pressure and consequently greater vaporization at that point results in a much lower temperature. Accordingly, it is an object ofthis invention to provide a device for inco'rporation'in the refrigeration system between the restricting tube and the evaporator which will prevent freezing of mois-' ture therein. g

It is another object of this invention toiprovide such a device having provision for, adjustmentfor use in lieu of the restricting tube as the sole means for maintaining the proper pressure difference between the high side and the low side of the refrigerating system.

vvFurtherIobjects'and advantages of this invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexted to and forming a, part of this specification. v

For a better understanding of this invention, reference maybe had to the accompanying drawing in which Fig. l is a view of a portion of a refrigerator incorporating the device for preventing the freezing of moisture in the restricting tube; Fig. 2 is an enlarged sectional view showing details of one form of this device; Fig. 3 is a sectional view taken along the line 3-3 of Fig.2; Fig. Lisa sectional view of a modified formof this device; Fig. 5 is a view of a portion of a refrigeratorincorporatin a modified form of this device .Whichactsas a sole means for controlling the flow of the liquid refrigerant in the system; and Fig. 6 is an enlarged view showing details of the modified form incorporated in the apparatus of Fig. 5. v

Referring to Fig. 1', the household refrigerator illustrated includes a, cabinet I having foodstorage compartment 2 cooled by an evaporator 3 j of the flooded type. A refrigerant liquefying unit 4 is mounted within a housing 5 on the topof the cabinet. This refrigerant liquefying unit comprises a hermetically sealed casing 6, which contains the motor-compressor unit, and a condenser I. The refrigerant is compressed by the motorcompressor unit and the compressed refrigerant passes through a conduit 8 to the condenser 1, where it is liquefied. The liquefying action is accomplished'by thecirculation of air over the condenser! by a'fanpnot shown) driven by a motor 9 or any otherfsuitable apparatus. The liquefied refrigerant passes, v from the condenser through a restricting tube or conduit in to a: new restricting device or element II. From the outlet of the device I l the refrigerant passes through a conduit l2 to the evaporator 3'. The refrigerant which is vaporized in the evaporator is withdrawn from the header- I 3 through a suction line' [4; the vaporized refrigerant passing through this line to the compressor. The suctionline l4 and the greaterportion of the restricting tube Hl'are secured together in heat exchange relation to insure vaporization of any liquid refrigerant which may be present inthe suction line. v,

Restricting ,tubesare employed in many mechanical. refrigerating systems .to provide for the maintenance ofa pressure differential between the high side of the refrigerating system andthe low side of the system. The pressure at the low side end of the restricting tube in' such systems maybe sufficiently low that the'vaporization of therefrigerant frequently reduces the temperature below the freezing point of water. This reduction in temperature results. in freezing any water present in the refrigerating systemand in the collection of ice in the restricting. tube near the outlet end thereofja'nd the. consequent blocking of the system. In the system illustrated in the drawing, the, total pressure differential between the high side and the lowside is divided between the restricting tube and the device ll. Furthermore, the device I l i s'incorporated inthe refrigeratingsystem between the restricting tube and the evaporator. Since a portion of. the t.ota1 pressure drop thus occurs across'thedevice .l l,; and sincelthispo'rtion is adjacent the low side of the system the' pressure at the low side end of the restricting tube will be maintained at a sufficiently high value that ice will not form in the restricting tube. Hence clogging of the restricting tube due to the formation of ice therein will be effectively prevented.

Referring now to Fig. 2, the details of one form of the device H are shown. The device includes a tube or conduit [5 ofsubstantially larger diameter than the restricting tube. End plates or members l6 are provided for each end of the tube l5. Suitable compressible moisture-absorbing material is included within the enlarged conduit l5 between the members IS in such a manner that the mass of such material extends across the entire cross-sectional area of the conduit l5. This material has the characteristic of transmitting liquid and gaseous refrigerant. In the form shown in Fig. 2 this material consists of felt disks or pads H, but other materials, such as filter paper, may also be used. The felt disks are assembled in the tube 15 and are compressed by the application of a predetermined pressure to the members It. While under pressure the members l6 are secured firmly to the tube l5 by welding or brazing or in any other suitable manner. The number of felt disks used and the pressure applied during this assembly are chosen, that is, the length and density of the felt are chosen, so that the felt disks will offer a sufficient resistance to flow of refrigerant as to secure the desired pressure drop across the device H during operation of the refrigeration system.

. Each member 16 is constructed with a longitudinal passage l8 in order to provide for the flow of refrigerant therethrough. In order to secure an even. distribution of the refrigerant from the passage. l8 over the entire surface of the disks H, the inner faceof one or both of the members [6 may be provided with suitable grooves. As shown in Fig. 3 a series of circumferential grooves 13 and a series of radial grooves 20 are formed in the face of the. closure member for this purpose.

' In Fig. 4 there is shown a modified form of the device I l which employs filter paper as the moisture-absorbing material. The filter paper, like the felt disks in the embodiment shown in Fig. 2,

has the characteristic of transmitting refrigerant.

In the embodiment shown in this figure the filter paper is in the form of thin disks 2| which extend across the entire cross-sectional area of the conduit l5. The same numerals have been applied to correspondingparts in Figs..2 and 4, and the construction employed in Fig. 4 is substantially the same as that described in connection with Fig. 2 except that perforated metal plates or disks 22 and 23 are incorporated between the members l6 and the filter paper 2|. 7 These perforated metal disks are included to prevent the filter paper, under compression, from being forced into the grooves in the faces of the closure members and blocking the free flow of refrigerant through these grooves. By the interposition of the perforated metal disks 22 and 23 the free flow of refrigerant from the passage [8 through the grooves 19 and 20 and over a wide area of the filter paper disks is insured.

In Fig. 5 there is illustrated a portion of refrigerating apparatus incorporating still another form of this invention. The same numerals have 7 been applied to corresponding parts in Figs. 1

and 5. In Fig. 5 the restricting tube utilized in the construction illustrated in Fig. 1 is. omitted, and the entire pressure differential between the high side and the low side of the refrigerating system is maintained by a flow-controlling de 4 vice or element 24. Liquid refrigerant is conducted from the condenser I to the device 24 through a conduit 25 which is of sufiicient diameter to'permit ready flow of the refrigerant without any substantial pressure drop. The refrigerant passes from the device 24 to the evaporator 3 through a conduit 26 which is of the same general construction as conduit l2 in the apparatus shown in Fig. 1.

Referring now to Fig. 6, the device 24 includes a tube or conduit 2'! of substantially the same diameter as the tube l5 shown in Figs. 2 and 4. An end plate or member 28, which is constructed in the same form as the members [6 previously described, is provided at one end of the tube 21. This end plate is secured to the tube 21 by welding or brazing or in any other suitable manner.

'Within the tube 21 is placed a mass of suitable fluid-transmitting material which extends across the entire cross-sectional area of the tube 21. In the embodiment shown in Fig. 6, this material is in the form of moisture-absorbin felt disks 29. In order that the pressure on the felt disks may be varied at any time during the operation of the system to secure a variation in the pressure differential between the high side and the low side of the system, an arrangement for adjusting the Pressure is incorporated in thedevice 24; A flat perforated metal disk or member 30, which is similar to the disks 22 and 23, is placed against the felt disks in order to provide a firm fiat surface for the application of the variable pressure on this material. An end plate or member 3| is secured in any suitable manner to the tube 21 and isprovided with a threaded openingv which is engaged by an adjusting screw 32. The end of the screw 32 fits in a groove 33 formed in a plate or member 34 and adjustment of the screw 32 forces the plate 34 against the perforated metal disks 3!! and varies the pressure on the felt disks 29. v In order to prevent any leakage of refrig-=, erant between the screw 32 and the end plate 3! an expansible element or, bellows '35 is secured between the plate 34 and a corresponding mendber 36 which is fixed to the end plate 3|. It can be seen that the bellows prevents leakage of refrigerant and still allows relative adjustment of the various members to alter the pressure on the felt disks 29. The bellows is constructed so that it has a natural tendency to contract. Hence whenever the screw 32 is adjusted toward the-lefthand end of the device 24 the bellows, incontracting, will move the plate 34 to the left and thereby reduce the pressure on the felt disks.

If felt disks are used as the moisture-absorbing material, it may be desirable to treat them before incorporation in the apparatus in order to remove any impurities such as soap, rosin, etc. This may be accomplished by washing the felt disks in a solution of carbontetrachloride and hot water and drying them at about C.

It can be seen that by this invention there has been provided a refrigerating system in which the freezing of any moisture contained therein is localized in the moisture-absorbing material which is contained in an enlarged tube where the freezing of moisture will not interfere with the flow of refrigerant, and that freezing of moisture within the restricting tube is thereby prevented. This is accomplished by incorporating the device containing the moisture-absorbing material into the refrigerating system between thev restricting tube and the evaporator, and by com pressing the moisture-absorbing material toan ext nt een insu es t at a .Suflicient portion or the total pressure drop between the high side and the-low side of the refrigerating system will occur across the moisture-absorbing element that the pressure at the low side end of the restricting tube will bemaintained above the point at which any freezing of water" could occur. By this invention there is also provided a flow-controlling device which is used as a substitute for the capillary tube and provision is made for a ready adjustment of the pressure on the moisture-absorbing material to control the pressure differential between the high side and the low side of the refrigerating system.

While this invention has been illustrated in connection with a household refrigerator having a compressor type refrigerating machine and while specific structures have been disclosed, it is not desired that this invention be limited to these particular embodiments and it is intended by the appended claims to cover all modifications within the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating system including a high side and a low side, anevaporator on the low side, means including a restricting conduit for conducting refrigerant from said high side to said evaporator, and means for maintaining the pressure in said restricting conduit above a predetermined minimum at which freezing of moisture would occur, said last-named means including a second conduit of larger cross-sectional area having moisture absorbing material therein extending across the entire cross-sectional area thereof, said second conduit being disposed between said restricting conduit and said evaporator the length and density of said moisture absorbing material in said second conduit being selected so that the relative resistances to flow of refrigerant offered by said conduits are such that any pressures below said predetermined minimum will occur in said second conduit and any freezing of moisture will be localized in said moisture-absorbing material.

2. In a refrigerating system including a high side and a low side, an evaporator on the low side, means including a restricting conduit for conducting refrigerant from said high side to said evaporator, and means for maintaining the pressure in said restricting conduit above a predetermined minimum at which freezing of moisture would occur, said last-named means including a second conduit of larger cross-sectional area having felt disks therein extending across the entire cross-sectional area thereof, said second conduit being disposed between said restricting conduit and said evaporator whereby any pressures below said predetermined minimum will occur in said second conduit and any freezing of moisture will be localized in said felt disks.

3. In a refrigerating system including a high side and a low side, an evaporator on the low side, means including a restricting conduit for conducting refrigerant from said high side to said evaporator, and means for maintaining the pressure in said restricting conduit above a predetermined minimum at which freezing of moisturewould occur, said last-named means including a second conduit of larger cross-sectional area having paper disks therein providing a mass of moisture-absorbing material across the entire cross-sectional area thereof, said second conduit being disposed between said restricting conduit and said evaporator whereby any pressures below said predetermined minimum will occur in said second conduit and any freezingof moisture will be localized in said paper disks. I

4. In a refrigerating system including a high side and a low side, an evaporator on the low side, means for conducting refrigerant from said high side to said evaporator, said means including a restricting conduit and a second conduit of larger cross-sectional area than said restricting conduit, and moisture-absorbing material extending across the entire cross-sectional area of said second conduit, said second conduit being disposed between said restricting conduit and said evaporator, the relative resistances to flow of refrigerant ofiered by said conduits being such that all pressures below that at which freezing of moisture will take place in said means occur within said moisture-absorbing material in said second conduit.

5. In a refrigerating system, an evaporator, means for controlling the flow of refrigerant to said evaporator, said means including a restricting conduit and a second conduit of larger crosssectional area than said restricting conduit, said second conduit being disposed between said restricting conduit and said evaporator, a mass of moisture-absorbing material within said second conduit and extending across the entire crosssectional area thereof, and means for causing said refrigerant to be distribute-d over a large area of said moisture-absorbing material, the relative resistances to flow of refrigerant offered by said conduits being such that all pressures below that at which the freezing of moisture will take place in said controlling means occur within said moisture-absorbing material in said second conduit.

6. In a refrigerating system, an evaporator, a

restricting conduit for conducting refrigerant tothereof, at least one of said end members having a plurality of radial and concentric grooves on the inner face thereof to provide passages for distributing said refrigerant over a large surface of said moisture-absorbing material.

7. In a refrigerating system, an evaporator, a

I restricting conduit for conducting refrigerant toward said evaporator, means for maintaining the pressure in said restricting conduit above a predetermined minimum at which freezing of moisture would occur, said means including a second conduit of larger cross-sectional area arranged between said restricting conduit and said evaporator, said second conduit including end members, a passage through each end member, one of said passages being associated with said restricting conduit and the other of said passages being'associated with said evaporator, and felt disks within said second conduit and extending across the entire cross-sectional area thereof, at least one of said end members including means for distributing said refrigerant over a large surface of said felt disks.

8. In a refrigerating system, an evaporator, a restricting conduit for conducting refrigerant toward said evaporator, a second conduit of larger cross-sectional area arranged between said restricting conduit and said evaporator, said second including end members, a passage conduit including end members, a passage through each end member, the passage through one of said end members being associated with said restricting conduit and the passage through the other of said end members being associated with said evaporator, paper disks within said second conduit providing a mass of moisture-absorbing material extending across the entire cross-sectional area thereof, said end members having grooves on the inner faces thereof to distribute refrigerant over a large surface of said paper disks, and a perforated metal disk between each of said end members and said paper disks to prevent said paper disks from blocking said grooves.

WILLIS R. WHITNEY.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,866,659 Litle July 12, 1932 2,225,990 Henry Dec. 24, 1940 2,319,498 Gerard May 18, 1943 2,430,692 Touborg Nov. 11, 1947 FOREIGN PATENTS Number Country Date Great Britain June 20, 1949 

